Hi,Welcome to Just Answer, My name isXXXXX will be helping you with your appliance issue today.
Start this at the beginning of the cycle let it fill then opened the door and tell me how much water is in the bottom of the machine after it fills, in inches if you can, thanks. Bryan
You should have water right up to the heater in this, you're not getting enough water therefore not enough water pressure when is enough water pressure this lifts the arm up so it spins freely, your fill valve needs to be replaced, it's not letting enough water in the allotted time in the fill cycle, these valves can get stuck and not open fully, therefore enough water doesn't come in and won't wash correctly, this is located behind the bottom access panel under the door, you can order this online at
http://www.repairclinic.com/PartDetail/Water-Inlet-Valve/1678?modelNumber=PDB3430AWX for $28, or pick one up locally if you have a supply house nearby, one other thing to check for ordering this is to make sure your float isn't sticking that's inside the dishwasher make sure it lifts up and down easily, thanks, Bryan
Okay, I'm sending you the diagram of the spray arm assembly so you can take a look and get this apart to see what may be funding this up usually the spray arm just rides on number 22 in the diagram, unless theres something like a piece of plastic wrapped around inside the spray arm tower part number 22 may be missing or broken,
you need to unscrew part number 33 counterclockwise to remove the spray arm assembly hope this helps thanks, Bryan